This graph shows the percentage abundance of five gases in the atmosphere of Mars, as measured by the Quadrupole Mass Spectrometer instrument of the Sample Analysis at Mars instrument suite on NASA's Mars rover October 2012. The season was early spring in Mars' southern hemisphere, and the location was inside Mars' Gale Crater, at 4.49° south latitude, 137.42° east longitude. The graph uses a logarithmic scale for volume percentage of the atmosphere so that these gases with different concentrations can all be plotted. By far the predominant gas is carbon dioxide, making up 95.9 percent of the atmosphere's volume. The next four most abundant gases are argon, nitrogen, oxygen, and carbon monoxide. Researchers will use SAM repeatedly throughout Curiosity's mission on Mars to check for seasonal changes in atmospheric composition. // Credit: NASA/JPL-Caltech/SAM/GSFC